Liquid crystal is a substance that does not radiate light, but instead receives light and is capable of manipulating the received light. This means that a liquid crystal display device requires a light source in order to display images and data. In a typical liquid crystal display device, a backlight module using electric energy supplies the light, and a light guide plate in the backlight module converts the supplied light into uniform surface light for displaying of the images.
The light guide plate is one of the key components of a backlight module for ensuring that the surface light has uniform brightness and color. For example, a typical light guide plate converts a linear light source (such as a lamp) into a surface light source by changing pathways of light emitted from the lamp. In particular, reflection dots formed on the light guide plate help improve brightness and uniformity of the surface light obtained.
Taiwan Patent No. 552,439 issued on Sep. 1, 2003 provides a light guide plate with two light emitting surfaces, and part of the light guide plate is represented in FIG. 4. The light guide plate 4 includes a light receiving surface (not shown), two opposite light emitting surfaces 42, 43, and numerous light dividing parts 44 distributed in inclined orientations within the light guide plate 4. Each light dividing part 44 has one convex surface 441 and one plate surface 442. The convex surface 441 generally faces toward the light receiving surface (not shown), and divides incident light beams into two parts: reflection beams and refraction beams. The reflection beams propagate through the light emitting surface 42, and the refraction beams propagate through the light emitting surface 43.
This kind of light guide plate has a number of problems, including: (1) the structure is complicated, and it is not easy to manufacture the light guide plate 4; (2) the light dividing parts 44 are made in the light guide plate 4 by injection molding, and the shape of the light dividing parts 44 may be damaged when drawing of patterns; (3) because the shape and alignment of the light dividing parts 44 are difficult to make precisely, it is not easy to control the brightness and uniformity of light emitted from the light guide plate 4.
In consideration of the problems of the prior art, what is needed is a light guide device that has a simple structure and provides good brightness and uniformity of light emission.